Dextrocardia

Dextrocardia situs inversus refers to a condition in which the heart is a mirror image of normal placement. With dectrocardia the main mass of the heart sits right of the mediastinum. When all visceral organs are mirrored the condition is dextrocardia situs totalis.

The above chest X-ray is not reversed, that is a patient with dextrocardia.

All of the heart chambers and great vessels are reversed, as seen above.

Above is a comparison of a normal heart and the heart of a patient with dextrocardia

As you can imagine, there are multiple ECG changes found on the patient with dextrocardia. If you know the patient has this condition, it may be in your best interest to mirror normal electrode placement.

Take a look at some 12-leads of dextrocardic patients below:

Notice the obvious change in axis. A negatively deflected lead I would indicate right axis deviation. When leads II &amp; III become deflected in addition, this would indicate extreme right axis deviation (ERAD). ERAD is most often seen when impulses originate in the ventricles as with ventricular tachycardia, or ventricular pacemakers. ERAD may appear with dextrocardia.

When you see a negative QRS in lead I, and a positive QRS complex in aVR, you should first suspect misplaced leads. If they are placed correctly, dextrocardia should enter your differential.

Burhan Ahmed, MD, MACP, MSc is currently Editor-in-Chief at Medicalopedia.org. He completed his residency from Michigan State University in 2015. He has has 14 publications to his name. He is pursuing career in dermatology and practices at Clinique de Dermatology.